Effect of SO_2 on Catalytic Oxidation of HC and CO in Diesel Exhaust over Pt/γ-Al_2O_3

The effect of SO_2 on the catalytic oxidation behavior of HC and CO in simulating diesel exhaust was studied over fresh and 400℃ sulfated 2. 5g/L Pt/γ-Al_2O_3 using a fixed-bed flow reactor with temperature programmed reaction(TPR). The results showed that the inhibiting effect of SO_2 in the feed gas on the oxidation of HC and CO over fresh Pt/-Al_2O_3 as a result of SO_2 ad- sorbed species formed on the surface of catalyst; the promoting effect of SO_2 on conversion of C_3H_6 over sulfated Pt/γ-Al_2O_3 be- cause the SO_2 adsorbed species were oxidized to sulfate species on the Pt and γ-Al_2O_3 interface which strongly promote C_3H_8 oxi- dation. SO_2 in the automotive exhaust presents inhibiting effect over Pt catalytic converters at present, however. the results showed in this study tell us that SO_2 pretreatment at 400℃ might promote the C_3H_8 oxidation in the diesel exhaust.